Lens control for lithography tools

ABSTRACT

Embodiments described herein relate to a dynamically controlled lens used in lithography tools. Multiple regions of the dynamic lens can be used to transmit a radiation beam for lithography process. By allowing multiple regions to transmit the radiation beam, the dynamically controlled lens can have an extended life cycle compared to conventional fixed lens. The dynamically controlled lens can be replaced or exchanged at a lower frequency, thus, improving efficiency of the lithography tools and reducing production cost.

BACKGROUND

In semiconductor manufacturing, lithography tools are used to applypatterns onto substrates by selectively exposing photoresist layers onthe substrates to a radiation beam. Optical lenses are used in alithography apparatus to direct the radiation beam from a radiationsource to the substrate being processed. Optical lenses in lithographytools are made of fine quality materials and need to be replacedregularly because of contamination acquired during operation.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a schematic view of a lithography tool according to someembodiments.

FIG. 2A is a schematic view of a dynamic lens assembly according to someembodiments.

FIG. 2B is a schematic plan view of a dynamic lens and a first beamregion in alignment with an optical path in a lithography tool accordingto some embodiments.

FIG. 2C is a schematic plan view of the dynamic lens aligning a secondbeam region with the optical path according to some embodiments.

FIG. 2D is a schematic plan view of the dynamic lens and a plurality ofbeam regions according to some embodiments.

FIG. 3A is a schematic view of a dynamic lens assembly according to someembodiments.

FIG. 3B is a schematic view of a dynamic lens in a non-tilting positionaccording to some embodiments.

FIG. 3C is a schematic view of a dynamic lens in a tilted positionaccording to some embodiments.

FIG. 3D is a schematic plan view of a lens housing showing tiltingactuators according to some embodiments.

FIG. 4A is a schematic view of a dynamic lens assembly according to someembodiments.

FIG. 4B is a schematic plan view of a dynamic lens with translationactuators according to some embodiments.

FIG. 4C is a schematic plan view of the dynamic lens and a plurality ofbeam regions according to some embodiments.

FIG. 5A is a schematic view of a dynamic lens assembly according to someembodiments.

FIG. 5B is a schematic plan view of a dynamic lens with tilting andtranslation actuators according to some embodiments.

FIG. 6 is a flow chart of a method for performing a lithography processaccording to some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Embodiments described herein relate to dynamic lens used in lithographytools. In some embodiments, the dynamic lens includes one or moreactuators to align different regions on a lens surface with an opticalpath travelled by a radiation beam in a lithography tool. Duringoperation, multiple regions on the lens surface of the dynamic lens maybe sequentially aligned with the optical path. A plurality of substratescan be processed while the optical path aligns with each of the multipleregions.

FIG. 1 is a schematic view of a lithography tool 100 according to someembodiments. The lithography tool 100 is or includes an alignment andexposure tool, also known as a stepper and a scanner, configured totransfer circuit design patterns to a light sensitive layer on asubstrate. The lithography tool 100 may be an ultra violet (UV)lithography tool, an immersion lithography tool, an extreme ultra violet(EUV) lithography tool, an electron beam lithography tool, an x-raylithography tool, an ion projection lithography tool, or any suitableexposure tools using laser radiation source to generate a radiation beamfor exposure.

The lithography tool 100 includes a substrate stage 102 configured tosecure a substrate 104 for processing. In some embodiments, thesubstrate stage 102 includes a number of actuators configured to movethe substrate 104 in a number of degrees of freedom. In someembodiments, the substrate stage 102 is configured to move the substrate104 in six degrees of freedom—X, Y, Z, Rx, Ry, and Rz using any numberof actuators, such as six actuators.

The lithography tool 100 also includes a projection optics module 106.The projection optics module 106 includes a series of optical elements,such as optical lenses or mirrors, which function to reduce the size ofpatterns to be transferred to the substrate 104. In FIG. 1, theprojection optics module 106 includes a plurality of optical lensarranged in a series manner. In some embodiments, the projection opticsmodule 106 includes a plurality of mirrors arranged to deliver a lightbeam to the substrate stage 102.

The lithography tool 100 includes a mask stage 108 configured to securea reticle or a mask 110 thereon. The mask stage 108 and the substratestage 102 are positioned on opposite sides of the projection opticsmodule 106. The mask 110 has a pattern to be transferred to thesubstrate 104 through the projection optics module 106. In someembodiments, the mask stage 108 is movable and rotatable to align themask 110 for exposure. In some embodiments, the mask stage 108 includesa number of actuators configured to move the mask 110 in a number ofdegrees of freedom, for example, in six degrees of freedom—X, Y, Z, Rx,Ry, and Rz.

The lithography tool 100 further includes a condenser unit 112. Thecondenser unit 112 includes a plurality of optical elements, such asoptical lenses or mirrors, to focus a light beam towards the mask 110 onthe mask stage 108.

The lithography tool 100 is connected to a radiation source 122configured to provide a light beam for transferring patterns from themask 110 to the substrate 104. The radiation source 122 is configured toemit a light beam in an electromagnetic spectrum suitable for theexposure process to be performed in a desired lithography process. Theradiation source 122 may be configured to emit light beams in theultraviolet spectrum (such as extreme ultra violet (EUV), vacuum ultraviolet (VUV), and deep ultraviolet (DUV)), visible spectrum, x-rayspectrum, or microwave spectrum. In some embodiments, the radiationsource 122 is an excimer laser. In some embodiments, the radiationsource 122 is a mercury lamp. In some embodiments, a lens assembly 128is positioned between the radiation source 122 and the lithography tool100 to collect, condense, collimate, or otherwise prepare a light beamlithography processes.

Other optical elements, such as filters 114 and mirrors 116 may beoptionally positioned in the lithography tool 100 to direct a light beamfrom the radiation source 122 towards the substrate 104 on the substratestage 102 along an optical path 120. In some embodiments, otherelements, such as a shutter, a collimator lens, are positioned insuitable locations along the optical path 120 to facilitate exposureoperations in the lithography tool 100.

In some embodiments, the lithography tool 100 includes a housing 126.The housing 126 defines an inner volume. A vacuum pump, not shown, maybe connected to the housing to establish a vacuum environment in theinner volume. The substrate stage 102 is disposed in the housing 126 sothat the lithography process may be performed in a vacuum state. Othercomponents of the lithography tool 100, such as the condenser unit 112,the mask stage 108, and the projection optics module 106, may bedisposed in the same housing 126 or in individual housings.

In some embodiments, the lithography tool 100 includes alignment sensors118 positioned at various locations. The alignment sensors 118 are usedto guide the substrate stage 102 and/or the mask stage 108 to alignpatterns on the mask 110 with areas to be patterned on the substrate104.

In some embodiments, the lithography tool 100 further includes acontroller 124 connected to various components in the lithography tool100. In some embodiments, the controller 124 is configured todynamically control optical elements, such as lenses and mirrors, in thelithography tool 100 during operation. For example, the controller 124sends commands to move an optical element to align various regions ofthe optical element with the optical path 120.

During operation, the optical elements, the substrate stage 102, and themask stage 108 are moved to suitable positions so that the radiationbeam from the radiation source 122 travels through the optical path 120to convey a pattern on the mask 110 to the substrate 104. Duringoperation, the radiation beam emitted by the radiation source 122 isdirected to the condenser unit 112 through filters 114, the mirrors 116,and other optical elements. The condenser unit 112 focuses the radiationbeam for patterning. In some embodiments, the radiation beam transmitsthrough the mask 110 and carries the pattern in the mask 110. Theprojection optics module 106 shrinks the patterned radiation beam andprojects the radiation beam towards the substrate 104.

The substrate 104 is a semiconductor substrate on which integratedcircuit devices are to be formed. The substrate 104 has a photoresistlayer formed thereon. In operation, the radiation beam is incident onthe radiation sensitive photoresist layer transferring the patterncarried in the radiation beam to the photoresist layer. In someembodiments, the photoresist layer may include a chemically amplifiedresist (CAR). Alternatively or additionally, the photoresist layer mayinclude a metal based photoresist. For example, the photoresist layermay include a metal-oxide resist on top of a sacrificial carbon layer,such as spin-on-carbon. The photoresist layer may also be included in atri-layer mask having a bottom layer, a middle layer, and a top layer.The bottom layer may be a carbon organic layer. The middle layer may bea silicon-containing carbon layer used to help pattern the bottom layer.The photoresist layer may be the top layer.

As discussed above, the radiation beam travels along the optical path120 during lithographic processes. Typically, the same lithographyprocess is repeatedly performed on multiple substrates and/or multipleregions on a substrate. After performing a certain number of exposures,some optical elements may become contaminated, particularly at locationsthrough which the optical path passes. The optical elements are fixed inposition and the optical path 120 passes through a work region onoptical elements, for example, near the center of a lens or center of amirror. Traditionally, when the beam region on an optical elementbecomes contaminated, the optical element needs to be replaced.

In some embodiments, optical elements, such as lenses and mirrors, inthe lithography tool 100 are dynamically controlled and movable to usemore than one region on the optical elements as a beam region, e.g., thearea of the optical element upon which the radiation beam is incidentduring operation. The dynamically controlled optical element movesrelative to the optical path 120 to use different areas as a beam regionwhen contamination has built up in another (e.g., previously used) beamregion. The dynamically controlled optical element allows multiple areason the optical element to be used as a beam region, thereforemultiplying the lifespan of the optical element.

FIG. 2A is a schematic view of a dynamic lens assembly 200 according tosome embodiments. FIGS. 2B-2D are schematic plan views of a lens unit inthe dynamic lens assembly 200.

The dynamic lens assembly 200 may be used in lithography tools, such asthe lithography tool 100. In some embodiments, one or more opticalmodules in the lithography tool 100 include a dynamic lens assemblysimilar to the dynamic lens assembly 200. For example, the projectionoptics module 106, the condenser unit 112, or the lens assembly 128 caneach include a dynamic lens assembly similar to the dynamic lensassembly 200.

The dynamic lens assembly 200 includes one or more lens units 202 a, 202b, 202 c, 202 d, and 202 e. Even though lens units 202 a-202 e are shownin FIG. 2A, the dynamic lens assembly 200 may include more or less lensunits according to other examples.

The dynamic lens assembly 200 is disposed between a radiation source 204and an appliance 206 to convey a radiation beam from the radiationsource 204 to the appliance 206. In some embodiments, intermediatecomponents may be positioned between the radiation source 204 and thedynamic lens assembly 200, or between the dynamic lens assembly 200 andthe appliance 206. The radiation source 204 can be any suitable sourceconfigured to generate a light beam for using in a photolithographyoperation. For example, the radiation source 204 is configured togenerate a laser radiation beam, a UV beam, a microwave light beam, oran x-ray beam. In some embodiments, the radiation source 204 is a laserradiation source configured to provide a laser radiation beam to alithography tool. The appliance 206 includes any device or componentthat is downstream to the dynamic lens assembly 200 using the radiationbeam for an operation. In some embodiments, the appliance 206 is alithography tool, such as the lithography tool 100.

Each lens unit 202 a-202 e includes a lens 210, a frame 212 disposedaround the lens 210, and an actuator 214 positioned to move the lens210. The lens 210 is an optical element that refracts light passingtherethrough. The lens 210 has two surfaces 210 a, 210 b. The surface210 a faces an incoming light beam. The surface 210 b is opposing thesurface 210 a. Either one or both surfaces 210 a, 210 b arespherical-shaped to converge or diverge the incoming light beam on aprincipal focus. The surfaces 210 a, 210 b may be convex or concave toconverge or diverge the incoming light beam. The lens 210 shown in FIG.2A is a converging lens with two convex surfaces 210 a, 210 b. Duringoperation, an incoming radiation beam enters the lens 210 from thesurface 210 a and exits the lens 210 from the surface 210 b. In otherembodiments, the lens 210 is a converging lens with one convex surface.In some embodiments, the lens 210 is a diverging lens including at leastone concave surface. In some examples, the lens 210 is made of glass,fused silica, calcium fluoride, or any material suitable for refractinglight beams at wavelengths used for a photo lithography process. Thelens 210 in each lens unit 202 a-e may be different to achieve differentfunctions, may be the same, or any combination thereof.

The frame 212 is disposed around the edge of the lens 210. In someembodiments, the frame 212 is fixedly attached to the lens 210. Theactuator 214 is moveably coupled to the frame 212 to move the lens 210with the frame 212. In some embodiments, the actuator 214 is configuredto rotate the lens 210 about an optical axis 216 along the z-axis. Theoptical axis 216 passes through an origin 224 of the lens 210 (shownFIG. 2B). The optical axis 216 is along the z direction. The actuator214 rotates the lens 210 within a lens plane 230, which passes throughthe origin 224 of the lens 210 and is perpendicular to the optical axis216 of the lens 210. In some embodiments, the actuator 214 includes amotor.

During operation, a radiation beam travels along an optical path 218that traverses the lenses 210 in the lens units 202 a-202 e. In someembodiments, within at least one of the lens units 202 a-202 e, theoptical path 218 is at a distance away from the origin 224 of thecorresponding lens 210. FIG. 2B is a schematic plan view of the lens210. In FIG. 2B, a beam region 222 indicates an area where the opticalpath 218 intersects the lens 210. Thus, during operation, a radiationbeam traverses the lens 210 at the beam region 222. A center of the beamregion 222 is at a distance 220 away from the origin 224. When the lens210 rotates about the origin 224, the optical path 218 intersects thelens 210 at a new beam region 222′, as shown in FIG. 2C. FIG. 2D is aschematic plan view of the lens 210 showing a plurality of regions canbe aligned with the optical path 218 to serve as a beam region 222during operation.

During operation, contamination can gradually accumulate on the lens 210in the region where the radiation beam traverses the lens 210, such asthe beam region 222 in FIG. 2B. The contamination on the beam region 222can cause the transmission rate of the lens 210 to decrease, thus,decreasing in the efficiency of the lithography tool. Additionally, whena radiation beam, such as a laser beam, traverses a lens, the radiationbeam may create damage, such as compaction damage, to the lens. Thedamage to the lens may lead to loss of image quality in the lithographytool. Conventional lens units with fixed lenses require frequentreplacement or exchange when the beam region is contaminated or damaged.Lenses 210 in the lens units 202 a-202 e can be rotated to use a “fresh”region as a beam region when the beam region has contamination or hasbeen damaged. As a result, the lens units 202 a-202 e do not need to beexchanged or replaced as frequently as conventional lens units.

In some embodiments, the distance 220 between the origin 224 and thecenter of beam region 222 is selected to allow the optical path 218 toalign with multiple regions that are not significantly overlapping. Thelarger the distance 220, the greater the number of regions can be usedas beam regions, which can increase the life cycle of the lens unit 202a-202 e. However, a larger distance can lead to drift in the opticalpath, which may result in decreased image quality in the lithographyprocess. In some embodiments, a value of the distance 220 isapproximately a diameter of a circle that inscribes the beam region 222.

Referring back to FIG. 2A, a controller 208 is connected to the lensunits 202 a-202 e. In some embodiments, the controller 208 is connectedto the actuators 214 to control the rotation of the lens units 202 a-202e. In some embodiments, the lens units 202 a-202 e are arranged in amanner so that the origin 224 of each lens 210 in the lens units 202a-202 e passes the same optical axis 216. In some embodiments, the lensunits 202 a-202 e are rotated in synchronization to switch beam regionsat the same frequency. In other embodiments, the lens units 202 a-202 eare controlled independently from each other.

FIG. 3A is a schematic view of a dynamic lens assembly 300 according tosome embodiments. The dynamic lens assembly 300 is similar to dynamiclens assembly 200 except the dynamic lens assembly 300 includes lensunits having tilting actuators. FIG. 3B is a schematic view of a lensunit in the dynamic lens assembly 300 in a non-tilting position. FIG. 3Cis a schematic view of the lens unit in the dynamic lens assembly 300 ina tilted position. FIG. 3D is a schematic plan view of a lens housingshowing tilting actuators.

The dynamic lens assembly 300 includes one or more lens units 302 a, 302b, 302 c, 302 d, and 302 e. Even though lens units 302 a-302 e are shownin FIG. 3A, the dynamic lens assembly 300 may include more or less lensunits according to other examples. The dynamic lens assembly 300 isdisposed between the radiation source 204 and the appliance 206 toconvey a radiation beam from the radiation source 204 to the appliance206.

Each lens unit 302 a-302 e includes a lens 310, an inner frame 312disposed around the lens 310 and an outer frame 322. The lens 310 issimilar to the lens 210 described above. In some embodiments, the innerframe 312 is fixedly attached to the lens 310. A rotating actuator 314is moveably coupled to the outer frame 322 to rotate the lens 310 aboutan origin 324 of the lens 310 (shown in FIG. 3D). The actuator 314rotates the lens 310 within a lens plane 330, which passes through theorigin 324 of the lens 310 and is perpendicular to an optical axis 316of the lens 310. In some embodiments, the rotate actuator 314 includes amotor.

Each lens unit 302 a-302 e further includes one or more tiltingactuators configured to tilt the lens 310. In some embodiments, eachlens unit 302 a-302 e includes a respective tilting actuator 320 a, 320b, 320 c, 320 d (shown in FIG. 3D) to tilt the lens 310 around thex-axis and y-axis. The tilting actuators 320 a, 320 b, 320 c, 320 d arecoupled between the outer frame 322 and inner frame 312. Movements ofthe tilting actuators 320 a, 320 b, 320 c, 320 d adjusts the distancesbetween the outer frame 322 and the inner frame 312 along thecircumference of the inner frame 312 or the lens 310. Each tiltingactuator 320 a, 320 b, 320 c, 320 d is movable independently from oneanother. The combined movements of the tilting actuator 320 a, 320 b,320 c, 320 d result in the lens 310 tilting about the x-axis and/ory-axis. The tilting actuator 320 a, 320 b, 320 c, 320 c may be linearactuators (such as mechanical actuators), piezoelectric actuators,cylinders (such as pneumatic cylinders and hydraulic cylinders), or thelike.

In some embodiments, as shown in FIG. 3D, four tilting actuators 320 a,320 b, 320 c, 320 d are disposed along a circumference of the lens 310at 90 degrees apart. In some embodiments, while the lens 310 is in theposition shown in FIG. 3D, relative movements of the tilting actuators320 a, 320 b cause the lens 310 to tilt about the x-axis while relativemovements of tilting actuators 320 c, 320 d cause the lens 310 to tiltabout y-axis. Because positions of the tilting actuators 320 a, 320 b,320 c, 320 d relative to the x-axis and y-axis change when the lens 310rotates by the rotating actuator 314, movements of tilting actuators 320a, 320 b, 320 c, 320 d cause the lens 310 to tilt around different axes,although the same axes of rotation relative to the outer frame 322 maybe maintained. Other arrangements of the tilting actuators, such asthree actuators disposed along the circumference of the lens 310, can beused to achieve the same result.

During operation, a radiation beam travels along an optical path 318that traverses the lenses 310 in the lens units 302 a-302 e. In someembodiments, the optical path 318 is parallel to the optical axis 316.In some embodiments, within at least one of the lens units 302 a-302 e,the optical path 318 is at a distance away from the origin 324 of thecorresponding lens 310. Because of the optical path 318 is offset fromthe optical axis 316, the radiation beam may be no longer parallel tothe optical axis 316 after passing through the lens 310. For example, asshown in FIG. 3B, an incoming radiation beam 318 i is projected to thelens 310 along a direction parallel to the optical axis 316 and at adistance away from the optical axis 316. After traversing through thelens 310, an output radiation beam 318 o is no longer parallel to theoptical axis 316, instead the output radiation beam 318 o is at an angle326 from the optical axis 316.

In some embodiments, the lens 310 is tilted to correct the deviation ofthe optical path 318 caused by the offset between the optical path 318and the optical axis 316. As shown in FIG. 3C, the tilting actuator 320a extends while the tilting actuator 320 b retracts causing the lens 310to tilt about the x-axis. The optical axis 316′ after tilting is at anangel relative to the optical axis 316 prior to tilting. With theincoming radiation beam 318 i remaining parallel to the optical axis 316prior to tilting, the tilted lens 310 produces an output radiation beam318 o′ that is also parallel to the optical axis 316.

In some embodiments, a controller 308 is connected to the lens units 302a-302 e. In some embodiments, the controller 308 is connected to therotating actuators 314 and the tilting actuators 320 a-320 d to controlthe rotation and tilting of the lens units 302 a-302 e.

In some embodiments, the lens units 302 a-302 e are arranged in a mannerso that the origin 324 of each lens 310 in the lens units 302 a-302 epasses the same optical axis 316. During operation, an incomingradiation beam is projected to the lens units 302 a-e from an opticalpath that is parallel from the optical axis 316 but at a distance awayfrom the optical axis 316 to allow multiple regions being used as beamregions. Prior to operation, each lens 310 is rotate to have a “clean”region align with the optical path 318 and tilted at a suitable angle toensure that the optical path 318 remains parallel to the optical axis316. When the beam region in the lens 310 becomes contaminated ordamaged, the lens 310 is rotated to align a clean region with theoptical path 318. In some embodiments, the tilting angle is adjustedafter lens rotation.

Other arrangements of actuators can be used to achieve rotation andtilting of the lens 310. For example, the rotating actuator 314 iscoupled to the inner frame 312 and positioned to rotate the lens 310relative to the outer frame 322, and the tilting actuators 320 a, 320 b,320 c, 320 d are coupled to the outer frame 322 and positioned to tiltthe outer frame 322 and the lens 310 together.

FIG. 4A is a schematic view of a dynamic lens assembly 400 according tosome embodiments. The dynamic lens assembly 400 is similar to thedynamic lens assembly 200 except the dynamic lens assembly 400 includeslens units having translation actuators to move the lens. FIG. 4B is aschematic plan view of a lens unit in the dynamic lens assembly 400showing translation actuators. FIG. 4C is a schematic plan view of thelens showing an arrangement of usable beam regions.

The dynamic lens assembly 400 includes one or more lens units 402 a, 402b, 402 c, 402 d, and 402 e. The dynamic lens assembly 400 is disposedbetween a radiation source 204 and an appliance 206 to convey aradiation beam from the radiation source 204 to the appliance 206.

Each lens unit 402 a-402 e includes a lens 410, a frame 412 disposedaround the lens 410, and a translation actuators 414 x, 414 y positionedto move the lens 410 along the x-axis and y-axis respectively. The lens410 is similar to the lens 210 described above. The frame 412 isdisposed around the edge of the lens 410. In some embodiments, the frame412 is fixedly attached to the lens 410. The translation actuators 414x, 414 y are moveably coupled to the frame 412 to move the lens 410 withthe frame 412. The translation actuators 414 x, 414 y move the lens 410within a lens plane 430, which passes through an origin 424 of the lens410 and is perpendicular to an optical axis 416 of the lens 410. In someembodiments, the translation actuators 414 x, 414 y are linear actuators(such as mechanical actuators), piezoelectric actuators, cylinders (suchas hydraulic or pneumatic cylinders), or the like.

In some embodiments, a controller 408 is connected to the lens units 402a-402 e. In some embodiments, the controller 408 is connected to thetranslation actuators 414 x, 414 y to control the lens units 402 a-402e.

During operation, an incoming radiation beam is projected to the lensunits 402 a-e from an optical path 418. Prior to operation, each lens410 is moved by the translation actuators 414 x, 414 y to have a “clean”region align with the optical path 418. When the beam region in the lens410 becomes contaminated or damaged, the lens 410 is moved to align aclean region with the optical path 418. FIG. 4C schematicallyillustrates a plurality of beam regions 422 that can be used as beamregions. In some embodiments, the lens 410 is moved in a manner that thebeam regions 422 are used sequentially along a path 426.

FIG. 5A is a schematic view of a dynamic lens assembly 500 according tosome embodiments. The dynamic lens assembly 500 is similar to dynamiclens assembly 400 except the dynamic lens assembly 500 includes lensunits having tilting actuators. FIG. 5B is a schematic plan view of alens unit with tilting and translation actuators.

The dynamic lens assembly 500 includes one or more lens units 502 a, 502b, 502 c, 502 d, and 502 e. The dynamic lens assembly 500 is disposedbetween the radiation source 204 and the appliance 206 to convey aradiation beam from the radiation source 204 to the appliance 206.

Each lens unit 502 a-502 e includes a lens 510, an inner frame 512disposed around the lens 510, and an outer frame 522. The lens 510 issimilar to the lens 210 described above. In some embodiments, the innerframe 512 is fixedly attached to the lens 510. Translation actuators 514x, 514 y are moveably coupled to the outer frame 522 to move the lens510 within a lens plane 530, which passes through an origin 524 of thelens 510 and is perpendicular to the optical axis 516 of the lens 510.In some embodiments, the translation actuators 514 x, 514 y are linearactuators (such as mechanical actuators), piezoelectric actuators,cylinders (such as hydraulic or pneumatic cylinders), or the like.

Each lens unit 502 a-502 e further includes one or more tiltingactuators configured to tilt the lens 510. In some embodiments, eachlens unit 502 a-502 e includes tilting actuators 520 a, 520 b, 520 c,520 d (shown in FIG. 5B) to tilt the lens 510 around the x-axis andy-axis. The tilting actuators 520 a, 520 b, 520 c, 520 d are coupledbetween the outer frame 522 and inner frame 512. Movements of thetilting actuators 520 a, 520 b, 520 c, 520 d adjust the distancesbetween the outer frame 522 and the inner frame 512 along thecircumference of the inner frame 512 or the lens 510. Each tiltingactuator 520 a, 520 b, 520 c, 520 d is movable independently from oneanother. The combined movements of the tilting actuator 520 a, 520 b,520 c, 520 d result in the lens 510 tilting about the x-axis and y-axis.The tilting actuator 520 a, 520 b, 520 c, 520 c may be linear actuators(such as mechanical actuators), piezoelectric actuators, cylinders (suchas pneumatic cylinders and hydraulic cylinders), or the like.

In some embodiments, as shown in FIG. 5B, four tilting actuators 520 a,520 b, 520 c, 520 d are disposed along a circumference of the lens 510at 90 degrees apart. In some embodiments, relative movements of thetilting actuators 520 a, 520 b cause the lens 510 to tilt about thex-axis while relative movements of tilting actuators 520 c, 520 d causethe lens 510 to tilt about y-axis. Other arrangements of the tiltingactuators, such as three actuators disposed along the circumference ofthe lens 510, can be used to achieve the same result.

During operation, a radiation beam travels along an optical path 518that traverses the lenses 510 in the lens units 502 a-502 e. When theoptical path 518 is at a distance away from origins 524 of thecorresponding lenses 510, the radiation beam may deviate from theoptical path 518, similar to example in FIG. 3B. In some embodiments,the lens 510 is tilted to correct the deviation of the optical path 518caused by the offset between the optical path 518 and the origin of thelens 510.

In some embodiments, a controller 508 is connected to the lens units 502a-502 e. In some embodiments, the controller 508 is connected to thetranslation actuators 514 x, 514 y and the tilting actuators 520 a-520 dto control the translation and tilting of the lens units 502 a-502 e.

During operation, an incoming radiation beam is projected to the lensunits 502 a-502 e from an optical path that is offset from the origin524 of at least one lens 510 to allow multiple regions being used asbeam regions. Prior to operation, each lens 510 is translated to have a“clean” region align with the optical path 518 and tilted at a suitableangle to correct any deviation of the optical path 518 caused by theoffset between the optical path 518 and the origin 524 of the lens. Whenthe beam region in the lens 510 becomes contaminated or damaged, thelens 510 is translated to align a clean region with the optical path 518and the tilting angles of the lens 510 are adjusted according to thelocation of the new beam region.

Other arrangements of actuators can be used to achieve rotation andtilting of the lens 510. For example, the translation actuators 514 x,514 y are coupled to the inner frame 512 and positioned to translate thelens 510 relative to the outer frame 522, and the tilting actuators 520a, 520 b, 520 c, 520 d are coupled to the outer frame 522 and positionedto tilt the outer frame 522 and the lens 510 together.

FIG. 6 is a flow chart of a method 600 for performing a lithographyprocess according to some embodiments. The method 600 may be performedusing a lithography tool, such as the lithography tool 100, having adynamic lens assembly, such as the dynamic lens assembly 200, 300, 400,or 500 described above.

In operation 610, a region on a lens is aligned with an optical pathbetween a radiation source and a substrate stage in a lithography tool.The lens is positioned so that an incoming radiation beam traverses aregion on the lens that is at a distance away from the origin of thelens. The lens may be disposed anywhere between the radiation source andthe substrate stage. In some embodiments, the lens is in an opticalassembly between a radiation source, such as a laser source, and alithography tool. For example, the lens is in the lens assembly 128 inFIG. 1. In other embodiments, the lens is positioned in the lithographytool, such as in a condenser or in a projection lens module. Forexample, the lens is the condenser unit 112 or the projection opticsmodule 106 in the lithography tool 100 of FIG. 1.

In some embodiments, the region on the lens that is aligned with theoptical path is at a distance away from an origin of the lens. In someembodiments, the distance between the origin of the lens and a center ofthe region is about an outer diameter of the region, and aligning theregion with the optical path includes rotating the lens about an opticalaxis passing the origin of the lens. In other embodiments, aligning theregion with the optical path includes translating the lens in a planeperpendicular to the optical path. In some embodiments, the lens istilted along one or more directions to correct deviation of the opticalpath caused by the offset between the origin of the lens and the centerof the region.

In some embodiments, two or more lenses are positioned to align a regionat a distance away from an origin of the corresponding lens with theoptical path. In some embodiments, two or more lenses are positioned sothat an incoming radiation beam traverses a region on the lens at adistance away for the origin of the lens.

In operation 620, a radiation beam is transmitted along the optical pathto perform a lithography process on a substrate disposed on thesubstrate stage. The radiation beam may be any suitable radiation beam,such as a laser beam, an EUV beam, a UV beam, a x-ray beam, or the like.The lithography process may be a UV lithography process, an EUVlithography process, an immersion lithography process, or the like. Insome embodiments, a plurality of substrates and/or a plurality of areason a substrate are exposed consecutively during operation 620.

In some embodiments, operation 630 is periodically performed todetermine whether the region on the lens that aligns with the opticalpath is contaminated. In some embodiments, the determination is made bymeasuring an intensity loss of the radiation beam after beingtransmitted by the lens. For example, an intensity loss greater than athreshold value indicates a significant amount of contamination isaccumulated on the region. In some embodiments, the intensity loss canbe obtained using intensities of the radiation beam in the optical pathbefore and after the lens, which can be measured using sensorspositioned at locations before and after the lens. In some embodiments,the intensity loss can be obtained by monitoring intensity changes at alocation in in the optical path after the lens. In some embodiments,when a dynamic lens assembly, such as the dynamic lens assembly 200,300, 400, or 500, is used, the intensity loss is measured by anintensity difference between the radiation beam received from theradiation source 204 and the radiation beam output to the appliance 206.In some embodiments, the threshold value is in a range between about 10%to about 30%, for example about 20%.

If operation 630 concludes that the region is contaminated, operation640 is performed. If operation 630 concludes that the region is still ingood condition for a lithography process, operation 620 resumes. In someembodiments, operation 630 is omitted. Operation 640 can be performedafter a certain number of substrates are processed in operation 620.

In operation 640, the lens is adjusted so that a new region is alignedwith the optical path or adjusted to have the radiation beam traverse anew region on the lens. The new region is different from the priorregions. In some embodiments, aligning the new region with the opticalpath including rotating the lens about an optical axis passing theorigin of the lens. In other embodiments, aligning the new region withthe optical path including translating the lens in a plane perpendicularto the optical path. In some embodiments, tilting angles of the lens areadjusted in one or more direction to correct deviation of the opticalpath caused by the offset between the origin of the lens and the centerof the new region. After operation 640, operation 620 resumes.

Even though, refractive lens are described in the examples above,embodiments can be used with any suitable optical components, such asrefractive components (lens), reflective components (mirrors), magneticcomponents, electronmagnetic components, electrostatic components, orany combination thereof, to utilize multiple regions on an opticalsurface for operation, thus, extending life span of the opticalcomponents. Even though, dynamic lens are described with lithographytools, embodiments can be used in other optical tools.

Embodiments described herein relate to dynamically controlled lens usedin lithography tools. Multiple regions of the dynamic lens can be usedto transmit a radiation beam for lithography process. By allowingmultiple regions to transmit the radiation beam, the dynamicallycontrolled lens can have an extended life cycle compared to conventionalfixed lens. The dynamically controlled lens can be replaced or exchangedat a lower frequency, thus, improving efficiency of the lithographytools and reducing production cost.

Some embodiments provide a lens assembly comprising a lens unitconfigured to be coupled to or in a lithography tool. The lens unitincludes an optical lens, and an alignment actuator connected with theoptical lens. The alignment actuator is operable to move the opticallens within a lens plane, and the lens plane passes through an origin ofthe optical lens and is perpendicular to an optical axis of the opticallens.

Some embodiments provide a method. The method comprises aligning a firstregion on an optical lens with an incoming radiation beam, wherein acenter of the first region is at a distance apart from an origin of theoptical lens, transmitting the incoming radiation beam through the firstregion on the optical lens to perform a lithography process, andaligning a second region on the optical lens with the incoming radiationbeam, wherein the second region is different from the first region.

Some embodiments provide an apparatus. The apparatus includes aradiation source, a lithography tool, and a dynamic lens assemblypositioned in an optical path between the radiation source and asubstrate stage in the lithography tool. The dynamic lens assemblycomprises one or more lens unit, each lens unit comprising an opticallens, and an alignment actuator coupled to the optical lens, thealignment actuator being movable to align one of multiple regions on theoptical lens with the optical path.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A lens assembly, comprising: a lens unitconfigured to be coupled to or in a lithography tool and positioned inan optical path between a radiation source and a substrate stage in thelithography tool, the lens unit comprising: a plurality of opticallenses, each optical lens having an optical axis; each of the pluralityof optical lenses coupled to its own first frame; each of the firstframes coupled to its own second frame; and each of the first framescoupled to its own translation actuator, each translation actuator beingmovable to translate the first frame to which it is coupled in a planeperpendicular to the optical axis of the optical lens which is coupledto the same first frame so as to align one of multiple regions on theoptical lens with the optical path; and each of the first frames coupledto its own tilting actuator and each of the tilting actuators coupled toits own second frame, wherein each tilting actuator is operable to tiltthe optical lens, with which the tilting actuator is coupled via thefirst frame, along a first direction.
 2. The lens assembly of claim 1,further comprising a rotation actuator coupled to each of the firstframes and coupled to a motor.
 3. The lens assembly of claim 1, whereineach lens unit further comprises: a second tilting actuator coupledbetween the first frame and the second frame, wherein the second tiltingactuator is operable to tilt the optical lens along a second directiondifferent from the first direction.
 4. The lens assembly of claim 1,wherein the translation actuator comprises: a first linear actuatorpositioned to translate the optical lens along a first direction in thelens plane; and a second linear actuator positioned to translate theoptical lens along a second direction in the lens plane different fromthe first direction.
 5. The lens assembly of claim 3, wherein the eachtilting actuator is operable to tilt the optical lens about a firstaxis, and the second tilting actuator is operable to tilt the opticallens about a second axis.
 6. The lens assembly of claim 1, furthercomprising a controller connected to the each tilting actuator in thelens unit.
 7. A method, comprising: aligning a first region on anoptical lens with an incoming radiation beam, wherein a center of thefirst region is at a distance apart from an origin of the optical lens;transmitting the incoming radiation beam through the first region on theoptical lens to perform a lithography process; determining the firstregion is contaminated; aligning a second region on the optical lenswith the incoming radiation beam, wherein the second region is differentfrom the first region, the aligning a second region on the optical lensaccomplished by translating the optical lens in a plane perpendicular toan optical axis of the optical lens with a translation actuator coupledto a first frame coupled to the optical lens; and tilting the opticallens with a linear actuator, the linear actuator coupled between thefirst frame and a second frame.
 8. The method of claim 7, furthercomprising: aligning the second region on the optical lens by rotatingthe optical lens with a rotation actuator coupled to a first framecoupled to the optical lens and translating the optical lens with atranslation actuator coupled to the first frame coupled to the opticallens.
 9. The method of claim 8, wherein aligning the first regioncomprises: rotating the optical lens about an optical axis of theoptical lens.
 10. The method of claim 9, wherein aligning the firstregion further comprises: tilting the optical lens about a first axis.11. The method of claim 7, wherein the distance between the origin ofthe optical lens and the center of the first region is approximately adiameter of the first region.
 12. The method of claim 7, whereinaligning the first region further comprises: tilting the optical lensabout a first direction.
 13. The method of claim 7, wherein determiningthe first region is contaminated comprises measuring an intensity lossof the radiation beam after being transmitted through the optical lens.14. The method of claim 13, wherein the intensity loss is between about10% to about 30%.
 15. An apparatus, comprising: a radiation source; alithography tool; and a dynamic lens assembly having an optical axis,the dynamic lens assembly positioned in an optical path between theradiation source and a substrate stage in the lithography tool, whereinthe dynamic lens assembly comprises: one or more lens unit, each lensunit comprising: an optical lens having an optical axis; a first framecoupled to the optical lens; a second frame; a translation actuatorcoupled to the first frame, the translation actuator being movable totranslate the first frame to which it is coupled in a planeperpendicular to the optical axis of the optical lens and movable toalign one of multiple regions on the optical lens with the optical path;and a tilt actuator coupled between the first frame and the secondframe, the tilt actuator being movable to align the optical pathparallel to the optical axis.
 16. The apparatus of claim 15, wherein thetranslation actuator comprises: a first linear actuator positioned tomove the optical lens along a first direction; and a second linearactuator positioned to move the optical lens along a second directiondifferent from the first direction.
 17. The apparatus of claim 15,further comprising: a controller coupled to the tilt actuator and thetranslation actuator of each lens unit.
 18. The apparatus of claim 15,wherein the tilt actuator includes: three tilt actuators disposed alongthe circumference of the optical lens.
 19. The lens assembly of claim 1,wherein the tilt actuator includes three tilt actuators disposed alongthe circumference of the optical lens.
 20. The apparatus of claim 15,further comprising a rotation actuator coupled to the first frame, therotation actuator being moveable to align one of multiple regions on theoptical lens with the optical path.